Menstrual status and thermoregulatory responses of active adolescents during exercise in a cold environment

This study examined the interactions between the reproductive status and the thermoregulatory responses during exercise in the cold in girls involved in competitive sports. Four girls with established menstrual cycles comprised the eumenorrheic menarcheal group (EM) and 5 non-menstruating girls comprised the pre-menarcheal group (PM). During the first visit maximal oxygen consumption, height, weight and percent body fat (%BF) were measured. The second visit involved: a determination of metabolic rate in thermoneutrality (21°C) involving 10-min rest and 20-min cycling (30% of VCL max), and a cold stress test (5°C, 40% humidity, <0.3 m/s air velocity) involving 20-min rest and 40-min cycling (30% of VCL max.). Subjects in the EM group were tested twice in the chamber during the follicular and luteal phases. Pre-menarcheal subjects were found to have significantly (p<0.05) lower core temperatures during the final stages of cold exposure. Overall, body fat was not significantly correlated with core temperature in the cold, however there was a significant surface-to-mass ratio difference between the groups. While in the follicular phase, EM girls had a higher core temperature during cold exposure. Therefore, reproductive hormonal status seems to be an important factor in terms of cold tolerance in females during adolescence.

Basic Psychological Needs as mediators: An examination of the relationship between exercise and well-being

Grounded in Basic Psychological Needs Theory (Deci & Ryan, 2002), the present investigation examined whether psychological need satisfaction mediated the relationship between moderate-to-vigorous physical activity (MVPA) and well-being. Adopting a longitudinal design participants (N= 147) completed questionnaires assessing MVPA, well-being and perceived psychological need satisfaction in exercise contexts on three occasions separated by three weeks. A pattern of small-to-moderate correlations were noted between MVPA and indices of well-being (r12's ranged from .16 to .29). Multiple mediation analysis indicated that perceived psychological need satisfaction mediated the relationship between MVPA and well-being with perceived competence emerging as a unique mediator. Serial mediation analyses indicated the importance of ongoing psychological need satisfaction to well-being. Contexts that afford individuals the opportunity to engage in MVPA, as well as supports their need for competence, would be most advantageous for the promotion of psychological well-being.